This invention relates to the purification of water and wastewater such as municipal and industrial wastewater, and more particularly, to a liquid mineral oxide concentrate obtained from processing minerals extracted originally from natural deposits rich in various minerals, particularly aluminum, magnesium, potassium and iron.
The present invention has diverse applications in the environmental field to treat drinking water and industrial and municipal wastewaters to preserve the water quality. There are many processes for the treatment of water and wastewaters. The conventional water treatment processes comprise coagulation chemicals, such as aluminum and ferric salts, or the polyelectrolytes. Coagulation and rapid filtration are good to remove dissolved organic content by suitable chemical compositions. Disinfection has been used for a long time as a first treatment step before coagulation to oxidize ammonia and to disinfect the water. It has proved to be significant for the particle removal from waste waters and it has been abandoned widely due to the formation of toxic chlorinated products like trihalomethanes or haloacetic acids. Drinking water and wastewater treatments in urban areas include chemical treatment in the form of coagulation, flocculation installations such as dosing equipment, rapid mixing and slow flocculation chambers, and sludge removal and filtration followed by disinfection. However, a major portion of the world""s population has no access to the supply of water treatment chemicals.
Heavy metal contamination exists in effluents of many industries such as printed circuit boards, metal finishers, mining operations, land fill leachates, tanneries and other metal processing industries. Metals are not biodegradable but are bio-accumulative. Cadmium, chromium, lead, mercury and arsenic are known to cause various health disorders and diseases. Most of the metals pose a risk of metal contamination in surface and ground water resources. The following industries are the main sources of heavy metal contamination: metal finishers; stainless steel, automobile, aircraft and semiconductor industries; paper mills; tanneries; mining facilities; appliance manufacturing; inorganic chemical manufacturing; metal based pigments and dyes production; defense related industries; and dye house waste. Industrial wastewater containing heavy metals is generally treated with the following treatment technologies: precipitation, co-precipitation, adsorption, ion exchange, membrane separation reverse osmosis or electrodialysis, or combinations of two or more of these technologies. Other treatments for removing inorganic contaminants include distillation, evaporation, oxide-reduction, air stripping, and biological treatment.
Most metal finishers use physicochemical treatment systems comprising coagulation, flocculation and sedimentation, followed by filtration for effective removal of suspended solids and heavy metals using aluminum sulfate, calcium hydroxide, ferric chloride or ferrous sulfate as coagulants along with an organic polymer as a flocculent aid. However, most physicochemical treatment plants generate high volumes of sludge production associated with poor performance in the removal of copper, chromium, and nickel, and thus do not fulfill the strict effluent discharge limits imposed by state and federal environmental protection agencies. At the present time, dried sludge disposal cost is approximately $1.7-2.5/lb; operating and chemical cost is approximately $2.95/1000 gallons.
In general, the metal plating industries do not reuse treated wastewater in the plating process because of the unacceptable quality of the treated water.
The present invention addresses these concerns by providing liquid mineral oxide concentrates useful for water and wastewater treatment with the objective to flocculate, disinfect and/or oxidize the dissolved and suspended toxic materials. Improvements in treatment of drinking water, removal of heavy metals and treatment of municipal sewage wastewater are provided. The invention provides superior results, when compared with other known methods of water purification, at a fraction of the cost, since the starting material is a readily available natural mineral resource.
Briefly, one embodiment of the invention comprises a process for making a liquid mineral oxide concentrate useful as a flocculent, coagulant and/or disinfectant for the treatment of water and wastewater. The starting material for the process is extracted from a natural mineral resource, preferably a mineral deposit rich in aluminum, magnesium, potassium and iron. One such mineral deposit is of volcanic and marine origin in which the soil contains a natural mixture of zeolites (aluminosilicates such as Clinoptilolites) and perlites and with significant concentrations of aluminum, magnesium, potassium and iron. The minerals extracted from the natural mineral deposit are reduced in particle size and then heat treated by heating them in air to produce a controlled expansion of the starting material, leaving an expanded mass of mineral oxide-rich material. This includes oxides of aluminum, iron, magnesium and potassium. The heat treatment expands the particles several hundred times in size; but the heat treatment also is necessary to remove all organic constituents and water molecules from the expanded material. The expanded mineral oxide-rich material is then dissolved in a liquid carrier in which the expanded mineral oxides are soluble. This forms a solution which can either be alkaline or acidic and which contains the dissolved mineral oxides. This mineral oxide-containing solution can be used in various concentrations in the treatment of water and wastewater, including industrial and municipal wastewater.